Explanation:
Sprawling across hundreds of light-years, emission
nebula IC 1805 is a mix of glowing
interstellar gas and dark dust clouds.
Only about 7,500 light-years away,
stars were born in this region
whose nickname -
the
Heart Nebula - derives from its suggestive
shape (seen here sideways).
This gorgeous,
deep telescopic image
of the nebula is very colorful, but if you could travel
there and gaze across these cosmic clouds with your own eyes,
are those the colors you would really see?
The short answer is no, even though the image was made
with light visible to
the human eye.
Light from this and other glowing gas clouds
surrounding hot, young stars comes in very narrow bands of
emission characteristic of
energized atoms within the clouds.
In fact, the nebular glow is often dominated by
hydrogen atoms emitting light in only a
small fraction
of that broad region of the spectrum that
we see as the color red.
Adopting an
artificial color scheme
commonly used for narrow band images of
emission nebulae, this
beautifully detailed view shows the light
from sulfur atoms in red hues, with hydrogen in green,
and oxygen atoms in blue.